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1.
Christopher K. Njue Bharathi Nuthakki Abhay Vaze James M. Bobbitt James F. Rusling 《Electrochemistry communications》2001,3(12):297
Vitamin B12 (a cobalt corrin complex) mediated the reduction of methylene chloride in the presence of styrene to give cyclopropylbenzene in quantitative yields in DMF containing tetrabutylammonium bromide (TBAB) and acetic acid with current efficiency 45% and turnover rate 4-fold larger than a typical vitamin B12-mediated 6-membered ring cyclization. A pathway involving formation and electroreductive cleavage of a chloromethylene-CoIII intermediate to yield a chloromethylene radical that adds to styrene is suggested. The reaction is highly sensitive to solvent composition, and water in the solvent acts as a proton donor to facilitate production of 1-chloro-3-phenylpropane in a competitive pathway.
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Author Keywords: Cyclopropanation; Catalytic electrolysis; Vitamin B12; Electrosynthesis; Cyclopropylbenzene 相似文献
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Th. Lehotkay J. Ostermeier C. Ogric F. R. Kreil 《Journal of organometallic chemistry》1996,520(1-2):59-62
η2-Phosphinocarbebe complexes of tungsten show a different behaviour towards anionic nucleophiles. The cationic η2-phosphinocarbene complex
reacts with the thiophenolate anion PhS− via carbonyl substitution, whereas the corresponding trimethylphosphine substituted carbene complex
adds the cyclopentadienyl anion at the carbene carbon atom. A third reaction pathway is observed on treating
with lithium diethylamide, providing a neutral η2-phosphinovinyl complex.
] addiert, setzt sich das Thiophenolat-Ion mit dem Dicarbonyl-substituierten Homologen
unter Carbonyl-Substitution um. In Gegenwart on Lithiumdiethylamid wird eine vergleichbare Additions- oder Substitutionsreaktion nicht beobachtet. Vielmehr findet beim Komplex
eine Deprotonierung der CCarben-Methylgruppe unter Ausbildung eines neutralen Metalla-phospha-cyclopropan-Ringes mit exocyclischer Doppelbinding statt. 相似文献
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Zusammenfassung
Kationische η2-Phosphinocarbenkomplexe des Wolframs zeigen ein differenziertes Verhalten gegenüber anionischen Nukleophilen, Während sich das Cyclopentadienyl-Anion am elektrophilen Carbenkohlenstoffatom inFull-size image
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Fangzin Fu Hongyu Li Dongsheng Zhu Qunxin Fang Huade Pan Edward R. T. Tiekink Franois Kayser Monique Biesemans Ingrid Verbruggen Rudolph Willem Marcel Gielen 《Journal of organometallic chemistry》1995,490(1-2):163-171
The synthesis and characterization by 1H, 13C, 119Sn NMR and 119Sn Mössbauer spectroscopy of (Z)-1-[2-(triphenylstannyl)vinyl]-1-cycloheptanol,
(1), and (Z)-1-[2-tri-p-tolylstannyl)vinyl-1-cycloheptanol,
(2), are described, together with their halodemetallation by I2, Br2 and ICIl to yield derivatives of the types
(Ar = phenyl or p-tolyl, N = 1, 2; X = I, Br, Cl, respectively). The solid-state structures of four compounds have been determined by X-ray diffraction analysis. In the crystals of
(1) and
(2) the Sn atom has a tetrahedral geometry distorted towards trigonal bipyramid as a consequence of a close intramolecular contact with the hydroxyl O(1) atom of 2.742(3) Å and 2.768(3) Å, respectively. A trigonal bipyramidal geometry is found in
(12) and
(4), in which significant Sn---O(1) interactions are noted [2.437(8) Å and 2.407(8) Å, respectively]. 相似文献
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6.
The silver(I) oxide mediated reactions of the gold(III) dichloride complex [{C6H3(CH2
uCl2] 2a with thiosalicylic or salicylic acid gives the respective complexes [{C6H3(CH2
)-2}] 3a (X=S) or 6b (X=O), containing chelating thiosalicylate or salicylate dianion ligands. X-ray studies show that for the thiosalicylate system, the thiosalicylate sulfur atom is trans to the N,N-dimethylamino group, whereas in the structure of the salicylate complex, it is the carboxylate group that is trans to NMe2. Both complexes show puckered metallacycles in the solid state. Electrospray mass spectrometry (ESMS) shows strong [M+H]+ and [2M+H]+ ions for both the gold-thiosalicylate and -salicylate complexes, and these ions possess a high stability towards cone voltage-induced fragmentation. ESMS was also used to identify a minor impurity, the bis(cyclo-aurated) cationic complex [A
Me2)-2-(OMe)-5}2]+ in the starting dihalide complex 2a and in the product 3a. This complex can be formed by reaction of Me4N[AuCl4] with 2 equivalents of the organomercury precursor [Hg{C6H3(CH2NMe2)-2-(OMe)-5}Cl]. The biological (antitumour, antimicrobial and antiviral) activities are also reported, and these reveal the complexes have moderate to high anti-tumour, antibacterial and antifungal activity. 相似文献
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The enthalpies of formation of glycine and L-α-alanine are determined by two complementary techniques: combustion calorimetry and change of state (sublimation) calorimetry.
The values of the experimental and theoretical energy of conjugation of these two molecules (partially conjugated) and the energetical value of the C---N bond in Laidler's scheme, derived from the experimental enthalpy of atomization, are also given.
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Résumé
Les enthalpies de combustion à létat condensé de la glycine et de la L-α-alanine ont été déterminées à d'un calorìmetre isopéribolique à bombe rotative. Leurs valeurs à l'état standard à 298,15 K sont: δH°c = −(972,98±0,19) kJ mol−1 pour la glycine et ΔHδc = −(1621,45 − 0,48) kJ mol-1 pour la L-α-alanine. Les enthalpies de sublimation à l'état standard à 298,15 K ont été obtenues par calori- 相似文献8.
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Isidoro Izquierdo María T. Plaza Rafael Robles Concepcin Rodríguez 《Tetrahedron: Asymmetry》1996,7(12)
Bishydroxylation of methyl
1 with osmium tetraoxide proceeded with extremed high diastereoselectivity to give only methyl
2. Configurations of the new stereogenic centers (C-2,3) in 2 were determined by degradation of the C-5,6,7,8 fragment to the well-known methyl
7. Transformation of 2 into the required
10, was achieved by a methodology that implied, protection to 8, reduction of the ester group in 8 to a hydroxymethyl group in 9, and finally deprotection to the free
10. On the other hand, epoxidation reaction on
11 afforded only the corresponding 2,3-anhydro derivative 12 with
configuration, as could be demonstrated by degradation to (S)-1,2,4-trimetoxybutane 16, which synthesis is reported herein. 相似文献
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Irradiation effects of 35 MeV proton beam bombardment on polyaniline (PAn) have been studied. PAn was made by standard MacDiarmid method, and the irradiation was performed at ambient temperature lower than 20°C. A 511 keV γ photon was detected by γ spectrum analysis, and a nuclear reaction 14N(p,α)11C in collaboration of 12C(p,pn)11C took place. By means of chemical ionization, mass spectra of samples before and after ion bombardment were recorded. Experimental results showed that products such as
and cyclic compounds like
and
were produced. IR spectra and SEM micrographs gave results of vibrational frequency shifts and morphology consistent with mass spectrometry. Finally we conclude that high energy proton beam bombardment resulted in main-chain scission and carbonization of PAn. Although the electrical conductivity reduced from 0.72 to 0.62 S cm-1, it retained at the same level. This implies that PAn might be used under the influence of high energy radiation. 相似文献
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Sulfite ion reacts with mercury(II) ion in acid solution to form the mercury(I) ion. The reaction is rapid and quantitative. The mercury(I) ion absorbs at 237 nm with a molar
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5. Beer's law Data for Sulfite Complexes of Covalent Mercury(II) Compounds
SO2 (ppm) | ?HgCl2a | ?HgBr2 | ?Hg(Ac)2b | ?Hg(SCN)2 |
2.0 | 12,500 | 10,000 | 10,000 | 9,200 |
4.0 | 12,500 | 11,500 | 10,000 | 9,000 |
6.0 | 12,500 | 11,500 | 10,000 | 9,200 |
8.0 | 12,000 | 11,000 | 10,500 | 9,800 |
- a
- Molar absorptivity based on sulfite ion at 230 nm. Solution was 6.86 buffer.
- b
- Mercuric acetate solutions seemed to be somewhat unstable. absorptivity of about 25,000. The absorbance is linear over a range of approximately 0.5–5.0 ppm as SO2. Covalent mercury(II) compounds form a complex with sulfite, Hg(SO3)22?, which absorbs at 230 nm and shows a linear response over a range of 1–8 ppm as SO2.
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Chao-Wan Chang Ying-Chih Lin Gene-Hsiang Lee Yu Wang 《Journal of organometallic chemistry》2002,660(2):127-132
Treatment of the ruthenium complex [Ru]---
(3, [Ru]=Cp(dppe)Ru) containing a heterocyclic [1,3]-thiazine-4-thione six-membered-ring ligand with various organic halides results in alkylation at the thione sulfur terminus of the ligand to yield [Ru]---
][X] (4a, R=CN, X=I; 4b, R=Ph, X=Br; 4c, R=CH=CH2, X=I, 4d, R=p-C6H4CF3, X=Br). Similarly the reaction of 3 with HgCl2 at room temperature affords [Ru]---
][Cl] (5). Transformation of 5 to the cationic vinylidene complex {[Ru]=C=C(Ph)C(O)NHPh}2[Hg2Cl6] (6) readily occurred in the air. The structures of 4c and 6 are determined by single crystal X-ray diffraction analysis. 相似文献
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